Girih tiles

Girih tiles, by Wikipedia en.wikipedia.org/wiki?curid=1... / CC BY SA 3.0
#Islamic_architectural_elements
#Islamic_architecture
#Tessellation
#Islamic_art
#Girih
#Architecture_of_Iran
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Girih tiles Patterned Girih tiles Construction lines are usually hidden: geometric tiles on left, girih pattern on right.
Girih tiles are a set of five tiles that were used in the creation of Islamic geometric patterns using strapwork （girih） for decoration of buildings in Islamic architecture.
They have been used since about the year 1200 and their arrangements found significant improvement starting with the Darb-i Imam shrine in Isfahan in Iran built in 1453.
The five shapes of the tiles are: These modules have their own specific Persian names: The quadrilateral tile is called Torange, the pentagonal tile is called Pange,
the concave octagonal tile is called Shesh Band, the bow tie tile is called Sormeh Dan, and the decagram tile is called Tabl.
All sides of these figures have the same length, and all their angles are multiples of 36° （π/5 radians）.
All of them except the pentagon have bilateral （reflection） symmetry through two perpendicular lines.
Some have additional symmetries.
Specifically, the decagon has tenfold rotational symmetry （rotation by 36°）; and the pentagon has fivefold rotational symmetry （rotation by 72°）.
By the late 11th century, the Islamic artists in North Africa start to use "tile mosaic", which is the predecessor of tessellation.
By 13th century, the Islamic discovered a new way to construct the "tile mosaic" due to the development of arithmetic calculation and geometry-the girih tiles.
Girih are lines （strapwork） that decorate the tiles.
The tiles are used to form girih patterns, from the Persian word گره, meaning "knot".
In most cases, only the girih （and other minor decorations like flowers） are visible rather than the boundaries of the tiles themselves.
The girih are piece-wise straight lines that cross the boundaries of the tile...